Yumen oil sands were chosen as the experimental material to separated oil from oil sands through wet-grinding by light oil and washing treatment by washing agent. The tailing sands were characterized by XRD. The factors includingamount of light oil, amount of washing agent, concentration of washing agent, reaction temperature were also studied. The results showed under the reaction conditions of mass ratio of naphtha to oil sands 0.15, mass ratio of washing agent to oil sands 1.5, concentration of washing agent 8%,reaction temperature 80 ℃, the oil recovery could be up to 96.5%.